U.S. regulators on Friday rejected an appeal by environmental groups to ban an industrial chemical known as bisphenol-A, saying there was not enough scientific evidence of harm in humans.
The U.S. Food and Drug Administration however said its latest ruling on the petition brought by the Natural Resources Defense Council was not the final word and expressed support for further research on the safety of BPA.
The NRDC had sought a ban on BPA in food packaging, food containers, and other materials likely to come into contact with food, citing studies on animals that showed the hormone-disrupting chemical was linked to brain changes, chromosomal abnormalities and some cancers.
Some "emerging human research" has also suggested a possible link between BPA exposure and altered toddler behavior, miscarriage, diabetes, cardiovascular disease and erectile dysfunction, the NRDC has said.
"The FDA denied the NRDC petition because it did not have the scientific data needed for the FDA to change current regulations, which allows the use of BPA in food packaging," said a statement sent to AFP by FDA spokesman Doug Karas.
"While evidence from some studies have raised questions as to whether BPA may be associated with a variety of health effects, there remain serious questions about these studies, particularly as they relate to humans and the public health impact of BPA."
Karas added that research done by the FDA has shown that actual BPA exposure to human infants is 84-92 percent less than previously estimated.
Further studies in animals have also shown that BPA does not pass easily from pregnant rodents to their offspring, and in fact the BPA level was "so low it could not be measured," he said.
"Researchers fed pregnant rodents 100 to 1,000 times more BPA than people are exposed to through food, and could not detect the active form of BPA in the fetus eight hours after the mother's exposure." Karas said.
Animal studies also tend to be flawed because they often involve injections of BPA that boosts doses, rather than administering BPA orally through food that results in faster metabolism of BPA to an inactive form.
The NRDC's citizen petition was presented to the FDA more than three years ago. The group later sued the FDA for failing to respond, giving U.S. regulators until March 31 to issue an answer.
BPA is used in "polycarbonate" types of hard plastic bottles and as a protective lining in food and beverage cans.
The chemical became a concern some years ago, following evidence in lab animals of a toxic effect on the brain and nervous system.
Several countries have introduced voluntary measures or laws to stop the manufacture of baby bottles with BPA and published guidelines on safer use of these containers.